Cycling enthusiasts continue to seek improvement in their performance riding a bicycle. One barrier to such improvement has been ready accessibility to means for measurement of performance both generally and in specific road situations (hilly terrain for example).
One common means used to monitor training performance is the heart rate monitor. While this is a fine training tool, it does have drawbacks, including difficulty, from one ride to the next, in gauging cyclist's riding intensity. It is, therefore, difficult to determine if any progress has been made in training using only a heart rate monitor.
A better way to keep track of a cyclist's performance is to monitor the power generated during a ride, and devices directed to measurement of a cyclist's power output have been heretofore suggested and/or utilized. One approach utilized by a variety of devices provides for a custom machined crank wherein the crank spider fingers are modified, providing a certain amount of elasticity, strain gauges being attached to the modified crank spider fingers to sense and measure deflection, and thus loading, at the modified crank spider fingers when the cyclist begins to pedal. Other designs utilizing similar replacement structures utilize measurement by means of stationary light emitting diodes attached to the bike frame and slotted timing disks at the modified crank assembly (i.e., when there is no load on the pedals and the crank is rotated the slots will pass the LED's at the same time, but when there is a load on the pedals the disk attached to the elastic modified crank spider will lag a reference disk). Power is then calculated by multiplying derived torque by the cyclist's cadence. The results can be displayed and/or stored in an on board processor. Such devices as these, however, are very expensive and structurally invasive (requiring a specially manufactured crank assembly), and aesthetically unappealing.
Another approach heretofore known and/or utilized measures torque in the bottom bracket axle by sensing the stress developed during pedaling thereat. A magnetic band is attached to the axle under or near the chainring assembly and a series of coils are coupled to the chainring assembly, the coils measuring magnetic fields generated from the magnetic bands. As force is applied to the pedals, the bottom bracket axle and magnet ring are torsionally loaded and the loading causes the magnetic flux lines (permeability) to change, thereby causing the voltage reading from the coils to change. This change in voltage is proportional to torque, and is utilized as discussed hereinabove to calculate power. Such arrangements as these are, however, complex, expensive and of debatable accuracy (since the device measures torque at the bottom bracket axle, it only receives load data from the side of the crank not having the chainrings thereat, i.e., only half of the actual performance data is collected). As before, such arrangements tend to be quite invasive, requiring a great deal of machining and assembly to allow for all the sensing equipment required, and may also require crank structures that are non-standard.
As may be appreciated from the foregoing, improved methods and devices for gauging the power output of a cyclist could be utilized.